Due to the variety of physical activities in which people of all ages participate, it is inevitable that some will either incur or be susceptible to ankle injuries resulting from excessive, pathological motion of the foot. In fact, the ankle joint is one of the most frequently sprained joints in the body. The most common type of ankle sprain results from excessive inversion, in which the foot twists such that the sole of the foot moves toward the midline of the body. This type of sprain can be caused by the foot coming down on an uneven surface, or simply as a result of unexpected circumstances when involved in a sporting activity. For example, a sprain may occur if a person is blocked by another player while jumping to make a basketball shot, so that the person's weight is applied to a leg while the foot is angled beyond a balanced state.
A number of prior art devices exist to reduce the likelihood of such sprains from occurring. However, before discussing such prior art, it may be helpful to briefly review anatomical terms that are relevant to the foot, and motions of the foot. Three reference planes are commonly employed when referring to the foot, each plane bisecting the ankle. The transverse plane divides the top and bottom of the foot, the frontal plane divides the front and back of the foot, and the sagittal plane divides the left and right sides of the foot. The lateral side of the foot refers to the side of the foot away from the mid-line sagittal plane, while the medial side is the side closer to the mid-line sagittal plane. The dorsum of the foot is the top part of the foot, and the plantar surface of the foot is the sole of the foot. In the horizontal transverse plane that divides the foot into a top and bottom reference plane, abduction motion occurs when the foot rotates laterally or away from the center of the foot, and adduction motion occurs when the foot rotates medially or towards the center of the foot. In the vertical frontal plane that divides the foot into the front and back, inversion motion occurs when the foot twists such that the plantar surface of the foot faces toward the midline of the body, and eversion motion occurs when the foot twists such that the plantar surface of the foot faces away from the midline of the body. In the vertical sagittal plane that divides the foot into a left and right side, plantarflexion motion occurs when the foot moves downward from the tibia or away from the anterior leg and distally such that the angle between the foot and leg is increased; and dorsiflexion motion occurs when the foot moves upward towards the tibia such that the angle between the foot and leg is decreased. Of the above-mentioned motions, the ones most commonly implicated in lateral ankle sprains are excessive lateral frontal plane motion of the foot (i.e., inversion), and external rotation (transverse plane) motion of the leg.
Ankle sleeves, ankle wraps, and ankle foot orthoses are prior art devices that have attempted to prevent excessive motion which can result in a sprain, often referred to as pathological motion. Ankle sleeves are formed of elastic conforming material that encompass the foot and ankle, and usually employ an open heel design. Ankle wraps include either a sleeve base coupled with a strap positioned to stabilize the ankle or a lace-up design with medial or lateral stays to limit frontal plane motion. Ankle orthoses consists of plastic shells and stays that may be hinged to allow sagittal plane motion and limit frontal plane movements. Both ankle sleeves and ankle wraps provide a proprioceptive effect and some degree of mechanical stability. And, although ankle foot orthoses also provide mechanical stability, such orthoses only do so when the foot is flat on the ground and the ankle is in a “closed-packed” position. This design is ineffective when the ankle plantar flexes, because the rear foot and ankle can still invert and rotate within the fixed stays and within the shoe, enabling a sprain to occur.
U.S. Pat. No. 4,922,630 (Robinson) discloses a device that is included with a shoe and which has a leg engaging strap to provide support in one direction. This patent asserts that the design disclosed prevents inversion, while permitting a full range of eversion, plantarflexion, and dorsiflexion motion. However, the support disclosed in the Robinson patent does not provide any support to the forefoot, which is particularly vulnerable when the foot is in a plantarflexed position. Further, the device disclosed in this patent is integrated into a shoe. Thus, a separate support and shoe is required for every style or type of shoe that is worn when such support is desired.
U.S. Pat. No. 4,621,648 (Ivany) discloses an ankle support system including an ankle brace portion and a strap support portion. The ankle brace portion is removably attached to the user's foot. One or more straps are attached to the user's shoe, and the straps are connected to the ankle brace portion during use in a variety of wrapping patterns. The Ivany patent asserts that the support described therein restrains the joint from overextension and provides unimpeded motion of the ankle joint through its normal range of motion. The support disclosed in the patent includes an ankle brace that can be readily used with different footwear, but the straps that are disclosed appear to be permanently attached to specific shoes, such that one set of straps cannot be easily moved from one set of footwear to another. Because it encompasses parts of the foot that are normally enclosed by footwear, the ankle brace can interfere with the fit of certain styles of footwear, and the process of preparing the support for each use (i.e., donning the ankle brace, donning the item of footwear, and wrapping the straps about the ankle brace) is cumbersome. Significantly, the support disclosed in the Ivany patent, like the support disclosed in the Robinson patent, does not provide any support to the forefoot, which as noted above, is particularly vulnerable when the foot is in a plantarflexed position. Furthermore, the support disclosed by Ivany does not provide any tension band effect. A tension band, which can be selectively adjusted by a user, is likely to provide significantly more support than the ankle wrap disclosed by Ivany.
It would therefore be desirable to provide a method and apparatus for supporting a user's foot to reduce the likelihood of pathological motion resulting in a strain or injury. The method and apparatus should enable a relatively full range of normal motion, should easily be movable from shoe-to-shoe, and should provide support to the foot not just in neutral and dorsiflexed positions, but also in the plantarflexed position as well. The prior art does not teach or suggest a complete solution to the problems discussed above.